JP2001327936A - Cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device which is capable of cleaning an object to be cleaned in a satisfactory state inside a cleaning container without making a cleaning fluid flow stagnant by generating a significant shearing force on the surface of the object to be cleaned. SOLUTION: The cleaning device is equipped with a compressor 17 which compresses the cleaning fluid at a level above a critical pressure a heater 18 which heats up the cleaning fluid at a level above a critical temperature and a cleaning container 1 filled with the cleaning fluid whose condition is made supercritical by the compressor 17 and the heater 18. The cleaning container 1 houses a cage 2 which stores the object to be cleaned 3 and the cage 2 is rotatable and allows permeation of the cleaning fluid in the supercritical state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus for cleaning objects to be cleaned (various mechanical parts, silicon wafers, etc.) having contaminants adhered to the surface thereof, using a cleaning fluid, particularly a supercritical cleaning fluid.

[0002]

2. Description of the Related Art In the manufacture of electronic parts, optical parts, precision machine parts, and the like, dust, oils and fats such as cutting oil and polishing oil, water, metal powder, ceramic particles, polymer chemistry, and the like adhered in the manufacturing process. A precision cleaning process for cleaning and removing contaminants such as substances is provided.

[0003] The cleaning method adopted in the conventional precision cleaning process is a dipping method in which pure water, a chemical solution or an organic solvent is used as a cleaning agent, and the object to be cleaned is immersed in the cleaning agent, and a combination of immersion and ultrasonic waves is used. And a steam cleaning method of cleaning with a vapor obtained by evaporating a cleaning agent.

However, in the cleaning method using a cleaning agent,
When cleaning an object to be cleaned having fine holes or grooves that are difficult for liquid to penetrate, or an object to be cleaned having a complicated shape, contaminants easily remain inside the object, and it is difficult to obtain an excellent cleaning effect. . In the past, chlorofluorocarbon and trichloroethylene were often used as cleaning liquids, but these have become a major social problem in terms of environmental destruction such as destruction of the ozone layer, and their use is being abolished.

[0005] Under such circumstances, a cleaning method using a supercritical fluid such as carbon dioxide as a cleaning agent has recently been proposed. Supercritical fluids have a very high diffusion coefficient compared to liquids, have a very low viscosity, and can easily penetrate into fine pores and grooves, making them suitable for cleaning objects with complicated shapes. Because.

For example, Japanese Unexamined Patent Publication No. 11-207276 discloses a compressor 31 and a heater 32 as shown in FIG.
And a reaction vessel 33 and a fat and oil component recovery tower 34, forming a circulation loop, loading the object 35 to be degreased into the reaction vessel 33, compressing carbon dioxide to a critical pressure or higher by the compressor 31,
Further, the carbon dioxide compressed above the critical pressure is heated to a temperature above the critical temperature by the heater 32, and the stirrer 37 is rotated by the motor 36 in a state where a predetermined amount of the supercritical carbon dioxide fluid is accumulated in the reaction vessel 33. The reaction vessel 33
A cleaning device that agitates a supercritical fluid in the inside to degrease the object 35 to be degreased is described (hereinafter, “conventional cleaning device 1”).
).

[0007] Japanese Patent Application Laid-Open No. 10-43702 discloses that a liquid such as a liquid or a gas generated by cleaning an object to be cleaned with a supercritical fluid and then depressurizing and / or cooling the supercritical fluid is permeable. Store the object to be cleaned in the cleaning container,
A cleaning apparatus is described in which a cleaning container is rotated by the pressure energy of a fluid, a stirring means in the cleaning container is rotated by the pressure energy of the fluid, or a fluid is spirally circulated in the cleaning container by the pressure energy of the fluid. That is,
As shown in FIG. 4, when a pressurized fluid is supplied into the cleaning tank 43 from the supply port 41 of the cleaning tank 43 having the supply port 41 and the discharge port 42, the fluid flows into the cleaning vessel 44 and is inverted L-shaped. The object to be cleaned in the cleaning container 44 is cleaned while the cleaning container 44 rotates by the action of the plate 45. 46 is a bearing for supporting the cleaning container 44. As shown in FIG. 5, a cleaning tank 53 having a supply port 51 and a discharge port 52 is provided.
When the cleaning vessel 55 is placed on the inner ring 54 and a pressurized fluid is supplied from the supply port 51 into the cleaning tank 53, the agitation means 57 provided on the lower lid 56 is rotated by the pressurized fluid to perform cleaning. The object to be cleaned in the container 55 is cleaned. Further, as shown in FIG. 6, when a pressure fluid is supplied into the cleaning tank 63 from the supply port 61 of the cleaning tank 63 having a supply port 61 and a discharge port 62 in which the fluid is supplied in a tangential direction of the wall surface. The fluid is spirally circulated along the inner wall of the cylindrical body 64, and the object to be cleaned in the cleaning vessel 65 is cleaned (hereinafter, referred to as “conventional cleaning device 2”).

[0008]

However, the conventional cleaning apparatus 1 is a method of cleaning an object to be cleaned by fixing the object to be cleaned in the reaction vessel 33. The blades of the agitator 37 do not interfere with the object to be cleaned. Can not be larger than a certain
The stirrer 37 cannot give sufficient stirring energy to the fluid in the reaction vessel 33.

The conventional cleaning device 2 uses the pressure energy of the fluid to rotate the cleaning container, rotates the stirring means, and circulates the fluid in a spiral manner. Sufficient stirring energy cannot be obtained simply by using it.

That is, in order to enhance the cleaning effect on the object to be cleaned in the cleaning container, it is necessary to generate a large shearing force on the surface of the object to be cleaned. Since sufficient stirring energy cannot be applied to the surface of the object to be cleaned, a large shearing force cannot be generated. In addition, when the stirring energy is small, the flow of the fluid in the cleaning container stagnates, and the cleaning target is likely to have uneven cleaning.

The present invention provides a cleaning apparatus which can generate a large shearing force on the surface of an object to be cleaned, and can satisfactorily clean the object to be cleaned in a cleaning container without causing stagnation due to the flow of a cleaning fluid. Is to provide.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, there is provided a rotatable basket which is rotatable and capable of transmitting a cleaning fluid, and accommodates an object to be cleaned in the basket. By passing a supercritical fluid into the cleaning container and rotating the palanquin at a high speed, a large shear force is applied to the surface of the cleaning object by rubbing between the cleaning object and the fluid rotating with the palanquin. The contaminants generated and adhered to the object to be cleaned can be forcibly peeled off and dissolved and removed in a supercritical fluid.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a compressor for compressing a cleaning fluid above a critical pressure, a heater for raising the temperature of the cleaning fluid above a critical temperature, and a supercritical state using the compressor and the heater. A cleaning device comprising a cleaning container to which a cleaning fluid is supplied, and having a palanquin containing the object to be cleaned in the cleaning container, wherein the palanquin is rotatable and the cleaning fluid in a supercritical state flows through the palanquin. The first aspect of the present invention is a cleaning apparatus characterized by being capable of transmitting light, and the second aspect of the present invention is the above-described first or second aspect of the present invention, wherein the cleaning apparatus is provided with a stirrer in a palanquin. A cleaning device having a circulation pump in addition to a compressor, a heater, and a washing container, and a circulation loop from the compressor to the washing container via the heater and from the washing container to the compressor via the circulation pump. As the third invention, the first and second Or in the third invention, a cleaning device provided with a cleaning fluid purifying device in the circulation loop is a fourth invention, and in the first, second, third or fourth invention, the purifying device comprises a filter and A fifth aspect of the present invention is directed to a cleaning device that is an oil separation tank.

Examples of the cleaning medium usable in the cleaning apparatus of the present invention include fluids such as ethane, propane, butane, ammonia, nitrous oxide, and carbon dioxide. It is preferable to use carbon dioxide as the cleaning medium from the viewpoint of safety for workers and the environment. Further, a cleaning aid can be added if necessary. The cleaning conditions using the cleaning medium as a supercritical fluid are not particularly limited as long as the pressure and the temperature are within a range for maintaining the supercritical state of each cleaning medium.

The object to be cleaned, to which the cleaning apparatus of the present invention can be suitably used, includes electronic parts, optical parts and precision mechanical parts made of glass, ceramic, synthetic resin or metal.

According to the first invention, the object to be cleaned is accommodated in the palanquin in the cleaning vessel, and the cleaning fluid brought into a supercritical state by the compressor and the heater is filled in the cleaning vessel. When rotated in a supercritical fluid, a large shear force is generated on the surface of the object to be cleaned due to the rubbing between the object and the fluid rotating together with the palanquin, and contaminants attached to the object to be cleaned are removed. Dissolve and remove. By rotating the object to be cleaned in this way, the shearing force generated on the surface of the object to be cleaned is extremely increased as compared with the conventional cleaning apparatus, and the cleaning effect can be greatly improved.

If the palanquin is provided with a stirring blade, the effect of stirring the fluid is increased, so that the flow is less likely to stagnate. The mounting position of the stirring blade is not limited,
For example, it can be attached to the side or bottom of a palanquin.

Further, in addition to the compressor, the heater, and the washing container, a circulation pump is provided, and a circulation loop is formed from the compressor to the washing container via the heater, and from the washing container to the compressor via the circulation pump. Then, the supercritical fluid can be continuously supplied into the cleaning container, so that it is difficult to generate an uneven flow of the fluid in the cleaning container.

If a cleaning fluid purifier is provided in the circulation loop, the cleaning can be continued without deteriorating the cleaning performance of the supercritical fluid, so that an excellent cleaning function can be maintained for a long time.

If the purifying device is a filter and an oil separation tank, large foreign substances can be removed by the filter, and the oil can be separated by the oil separation tank.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram showing one embodiment of the cleaning device of the present invention. In FIG. 1, reference numeral 1 denotes a cleaning container, in which a mesh-shaped palanquin 2 is disposed.
An object to be cleaned 3 (a plurality of silicon wafers in this embodiment) is fixed in the inside. The palanquin 2 is rotated via a drive shaft 5 extending from a motor 4 which is a rotating means provided on the top of the washing container 1. Stirring blades 6a and 6b are attached to the side and bottom surfaces of the palanquin 2. Reference numeral 7 denotes a jacket through which the heat transfer medium flows. The heat transfer medium introduced into the jacket 7 from the path 8 as needed exchanges heat with the supercritical fluid in the cleaning vessel 1 and is discharged through the path 9. After the heat of the heat transfer medium is used as a heat source of a heater such as a heat medium heater, the heat is again introduced into the jacket 7 through the path 8. Thus, the heat transfer medium is circulated.

A supply port 10 and a discharge port 11 are provided at the top and bottom of the washing container 1, respectively. A circulation loop 12 extending from the discharge port 11 to the supply port 10 includes a circulation pump 13.
, Filters 14 and 15, an oil separation tank 16, a compressor 17, and a heater 18. 18a is a heat medium inflow path, and 18b is a heat medium outflow path. Reference numeral 19 denotes a valve, and reference numeral 20 denotes a pressure reducing valve. FIG. 2 is a perspective view showing one embodiment of the palanquin 2.

According to the cleaning apparatus configured as described above, the cleaning fluid (carbon dioxide in the present embodiment) is compressed by the compressor 17 to a pressure equal to or higher than the critical pressure.
The carbon dioxide compressed above the critical pressure by the heater 18 on the downstream side is heated above the critical temperature. In this way, a supercritical carbon dioxide fluid is generated, and the cleaning vessel 1
A supercritical carbon dioxide fluid is introduced inside. Next, the palanquin 2 is rotated via the drive shaft 5 by rotating the motor 4.
Then, gradually increase the rotation speed of the motor 4 to
Is rotated at a high speed (about 800 to 1200 revolutions / minute). Due to the rubbing movement between the supercritical carbon dioxide fluid and the object to be cleaned 3 caused by the high-speed rotation of the palanquin 2, an extremely large shear force is generated on the surface of the object to be cleaned 3 and adhered to the object to be cleaned 3. The contaminants are removed in a forcible manner and dissolve in the supercritical carbon dioxide fluid. In particular, since the stirring pegs 6a and 6b are attached to the palanquin 2 of this embodiment, the stirring effect for the supercritical carbon dioxide fluid is improved, and the flow of the supercritical carbon dioxide fluid in the cleaning vessel 1 is reduced. Will not occur. The mounting positions of the stirring blades 6a and 6b are not limited to the side surface and the bottom surface of the palanquin 2, but may be appropriately determined according to the type of the supercritical fluid or the type of the object to be cleaned to obtain a preferable stirring effect. Can be fitted with a stirring blade. Further, the shape of the stirring blade is not limited to the flat paddle blade, and a propeller or the like may be employed.

The supercritical carbon dioxide fluid in which the contaminants are dissolved as described above is transferred through the circulation loop 12 by the circulation pump 13 and reaches the filter 14 or 15.
This filter is a device for removing relatively large foreign matter dissolved in the supercritical fluid, and only one of the filters 14 and 15 is used during the washing with the supercritical fluid. Therefore, the valve 19 before and after the other filter 14 or 15 not used is closed, and the valve 19 is closed.
The supercritical fluid is not passed through the filter in which the filter is closed, and the filter is regenerated to prepare for the next filtration process.

Thus, the supercritical carbon dioxide fluid from which the large foreign matter has been removed is decompressed by the pressure reducing valve 20 to release the supercritical state, and the oil component is separated in the oil separation tank 16. The carbon dioxide is discharged outside through the connected path 21, and fresh carbon dioxide is introduced into the circulation loop 12 through the path 22. The carbon dioxide is compressed to a pressure equal to or higher than the critical pressure in the compressor 17, and then the carbon dioxide compressed to a pressure equal to or higher than the critical pressure in the heater 18 downstream of the compressor 17 is heated to a temperature equal to or higher than the critical temperature.
In this manner, a supercritical carbon dioxide fluid is generated, and the supercritical carbon dioxide fluid is introduced into the cleaning vessel 1.
Thereafter, in the same manner as described above, the cleaning of the object to be cleaned 3 in the cleaning container 1 is continued.

As described above, when the contaminants adhering to the surface of the object to be cleaned 3 are removed as a result of the cleaning with the supercritical carbon dioxide fluid, the contaminants protrude from the upper lid 1a and the lower body 1b of the cleaning container 1, respectively. The fastener (not shown) for connecting the flange 23 is removed, the upper lid 1a is opened, and the cleaned object 3 is taken out of the cleaning container 1.

[0027]

Since the present invention is configured as described above, the following effects can be obtained.

According to the first aspect of the present invention, it is possible to provide a cleaning apparatus capable of satisfactorily cleaning the object to be cleaned in the cleaning container by generating a large shear force on the surface of the object to be cleaned.

In particular, according to the second aspect of the present invention, since the effect of stirring the fluid is increased, there is an effect that the flow of the fluid in the cleaning container hardly stagnates.

In particular, according to the third aspect of the present invention, since the supercritical fluid can be continuously supplied into the cleaning vessel, it is difficult for the fluid to flow unevenly in the cleaning vessel.

In particular, according to the fourth and fifth aspects of the invention,
Since the cleaning can be continued without deteriorating the cleaning performance of the supercritical fluid, an excellent cleaning function can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a system diagram showing one embodiment of the cleaning device of the present invention.

FIG. 2 is a perspective view showing one embodiment of a palanquin arranged in a cleaning container of the cleaning device of FIG. 1;

FIG. 3 is a system diagram of a conventional cleaning device 1.

FIG. 4 is an exploded perspective view of an example of a conventional cleaning device 2.

FIG. 5 is an exploded perspective view of another example of the conventional cleaning device 2.

FIG. 6 is an exploded perspective view of still another example of the conventional cleaning device 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Washing container 2 ... Paragon 3 ... Object to be washed 4 ... Motor 6a, 6b ... Agitating blade 12 ... Circulation loop 14, 15 ... Filter 16 ... Oil separation tank 17 ... Compressor 18 ... Heating device

Claims (5)

[Claims] 1. A compressor for compressing a cleaning fluid above a critical pressure, a heater for raising the temperature of the cleaning fluid above a critical temperature, and a cleaning fluid in a supercritical state by the compressor and the heater are supplied. A cleaning apparatus comprising a cleaning container and having a palanquin containing the object to be cleaned in the cleaning container, wherein the palanquin is rotatable, and a cleaning fluid in a supercritical state can pass through the palanquin. Cleaning equipment. 2. The cleaning apparatus according to claim 1, wherein a stirring blade is provided on the palanquin. 3. A circulation pump is provided in addition to the compressor, the heater, and the washing container, and a circulation loop is formed from the compressor to the washing container via the heater, and from the washing container to the compressor via the circulation pump. The cleaning device according to claim 1 or 2, wherein 4. The cleaning device according to claim 1, wherein a cleaning fluid purifying device is provided in the circulation loop. 5. The cleaning device according to claim 1, wherein the purifying device is a filter and an oil separation tank.